Our automotive instrument panels typically include a urethane foam cast between an outer vinyl skin and a barrier film, the barrier film being adhered by an adhesive to a rigid retainer member. Conventionally, the instrument panel is made by vacuum forming or powder slush casting a vinyl outer skin and injection molding a hard plastic retainer. The hard plastic retainer provides structural rigidity to the member. An adhesive is applied to the retainer, a barrier film is vacuum formed over the adhesive. Optionally, the holes in the retainer of the type for allowing instruments to pass therethrough are closed. The retainer assembly and vinyl outer skin are loaded into a foam mold. Foam is poured into the mold providing adhesion between the barrier film and the outer skin.
The U.S. Pat. Nos. 4,228,115 to Gardner et al, issued Oct. 14, 1980, and assigned to the assignee of the present application, and 4,420,447 to Nakashima, issued Dec. 13, 1983, both relate to processes for producing foam moldings. The Gardner et al patent discloses a method including the step of masking openings with heat shrink plastic during the injection foam step. The Nakashima patent discloses a process of pinching film between two mold blocks while a foaming process is executed on a foam mold material to form integrally a foam layer on a film covered side of an insert with the film being pressed against a preapplied adhesive on the insert. The present invention differs from both of the aforesaid patents by preforming the barrier film as a separate part of an applique to be described.
Applique technology has been utilized with small flat surfaces because of limitations with adhesive systems. Heat distortion and problems of mating of slide fit parts have limited this technology. For example, instrument panels are subjected to high temperatures causing considerable stress as the vinyl components of the foam applique revert back to a flat sheet. The adhesive utilized must withstand the stresses at high temperatures.Adhesives used on small flat applique parts in accordance with the prior art do not have the performance characteristics necessary to hold the stresses of larger parts such as instrument panels. Further, when fitting a covering of a complex three dimensional shape, such as applying an applique to a retainer member of an instrument panel, some sliding must occur. A mating fit of this type is not possible if one of the surfaces is sticky.
The present invention provides a solution to the aforementioned problems by providing a novel applique process applicable to the manufacturing of automotive instrument panels.